The present invention relates generally to a valve for adjusting the closing speed of a door closer, and more particularly to a valve of the type wherein an axially extending generally cylindrical valve member having a tubular portion and a solid portion is received with sliding contact in a blind-end bore of a valve body which includes inlet and outlet conduits opening into the bore. The valve member is axially adjustable in the blind-end bore. The wall of the tubular portion has an opening spaced axially from the open end of the tubular portion. The inlet conduit and the opening are located so as to be positionable into communication in such a way that an axial adjustment of the valve member changes the cross-sectional area of the passage created between the inlet conduit and the opening.
In known valves of this type, an unpleasant hissing sound is produced when fluid passes through the opening in the wall of the tubular portion during opening and closing. These valves have the additional disadvantage that the opening is occasionally clogged due to the accumulation of dirt or other foreign substances.
It is, therefore, an object of the invention to provide a valve for adjusting the closing speed of a door closer which operates without the hissing sound described above.